Ratiometric and colorimetric probes with large stokes shift for sensing of exogenous hypochlorite in potato sprouts and industrial effluents

Being one of the important reactive oxygen species (ROS), hypochlorite ions (ClO-) are involved in the control of several pathological and physiological processes. However, overexpression of ClO- may prompt several disorders including cancer. Therefore, two fluorescein functionalized compounds with catechol (probe 1) and 2-naphthyl (probe 2) as substituents were synthesized through Schiff base reaction to recognize ClO- in food items and industrial samples. While probe 2 exhibited turn-off fluorescent response towards ClO- with limit of detection (LOD) of 86.7 nM, structurally alike probe 1 showed excellent ratiometric response with low detection limit (36.3 nM), large Stokes shift (353 nm), and 'fast' response time (15 s). 1H NMR titration experiments favored spiroring opening of probe 1 upon the reaction with ClO-. Probe 1 was successfully utilized for the monitoring of exogenous ClO- in industrial samples. Further, fabrication of probe coated fluorescent paper strips and recognition of ClO- in sprouting potato show diverse practical applicability of our probes.